This invention relates to a device which is useable to ensure that a hole has been formed perpendicular to a surface and, more particularly, to a device for indicating and measuring the angularity (i.e., the angular displacement or deviation), if any, of a straight-walled hole which is in a workpiece, with the angularity being measured with respect to (i.e., relative to) the planer surface where the hole has its entrance opening in the workpiece.
It is well known that it is important to determine if a straight-walled hole (as distinguished from a tapered-walled hole) which is formed in a workpiece is in fact "straight", i.e., perpendicular to the surface of a workpiece into which the hole is formed. The importance varies, but in aircraft it is of critical importance that holes intended to be straight are, in fact, straight. For example, if fasteners are installed in a crooked hole in a structural component of an aircraft, undue and unexpected stress will develop, with possible very unfortunate results. As a result, "straight" holes are routinely inspected to determine that they are straight.
It is also well known that prior art devices and methods used for determining if a hole is straight are time-consuming and, therefore, costly to use. It is equally well known that those devices which are used for the aforementioned purpose and are not time consuming are, nevertheless, complex in structure and, therefore, costly to manufacture or buy.